HIV Flashcards
What cells do HIV hijack?
T-helper cells
Describe briefly the pathogenesis of HIV infection
1: HIV binds T helper cell with it’s gp120 binding to T helper cells CD4
2: viral envelope fuses with t helper cell membrane and viral RNA enters cell
3: viral reverse transcriptase manufactures DNA from RNA
4: viral integrase integrates DNA to host DNA
5: viral DNA transcribed/translated = viral proteins
6: new virus assembled and bud out of T helper cell = t helper cell death
- infected t cells also killed by t killer cells
Describe the phases of HIV infection
1: infection
- infection mucosal CD4 cell, transport to regional lymph nodes, established infection within 3 days, dissemination virus
2: acute phase
- HIV Abs +ve in blood 3-12 wks
- within 2-4wks flu-like symptoms 80%/macular-papular upper body rash
- rapid replication virus and loss t helper cells
- v high risk transmission
- after few weeks T killer cells destroy t helpers and greatly reduce rate viral replication
3: asymptomatic infection
- prolonged phase (may last years)
- virus continues to replicate rapidly but no. kept in check by immune system
- may be no symptoms but increased tendency to suffer colds/infection that are slow to go away
- dormant diseases e.g shingles/TB reactivate
4: disease phase (AIDS)
- decreased no. of t helper cells and increased viral load
- opportunistic infections
- weight loss
- dementia
- kaposi sarcoma
What is an opportunistic infection?
-pathogen that doesn’t normally cause a disease in a healthy person
Pneumocystitis pneumonia = opportunistic infection
- what organism causes this?
- what CD4 threshold does this increase the risk for?
- what signs/symptoms are seen
- CXR
- how is this diagnosed?
- treatment?
- what prophylaxis for this exists?
Organisms:
-pneumocystitis jiroveci: most common infection seen/diffuse infection
CD4 threshold: <200
Symptoms: insidious onset/dry cough/SOB
Signs: exercise desaturation - ask patient to do exercise and see SOB
CXR: may be normal, interstitial infiltrates, reticulonodular markings
Diagnosis: BAL + immunofluorescence +/- PCR
Treatment: high does co-trimoxazole (+/- steroid)
prophylaxis: low dose co-trimoxazole
What kind of TB infection is more commonly seen in HIV patients?
- symptomatic primary infection/reactivation latent
- lymphodenopathy
- miliary TB
- extra-pulmonary TB
- multi-drug resistant TB
- immune reconstitution syndrome
Cerebral toxoplasmosis is an opportunistic infection that affects HIV patients:
- organism?
- CD4 threshold?
- what does this cause?
- signs and symptoms?
Organism: toxoplasma gondii
CD4: <150
Clinical features: reactivation latent infection/multiple cerebral abscesses
S/S: headache/fever/focal neurology/siezures/decreased conscious level/raised ICP
Cytomegalovirus is an opportunistic infection that affects HIV patients:
- CD4 threshold
- what does this cause?
- signs/symptoms
- what screening is done?
CD4 < 50 (late stage), reactivation of latent infection
can cause: retinitis, colitis, oesophagitis
S/S: decreased visual acuity, floaters, abdo pain, diarrhoea, PR bleeding
Screening: ophthalmic screening for all individuals <50 CD4
What skin infections are seen in HIV patients?
Herpes zoster - multidermatomal and recurrent
Herpes simplex - extensive, hypertrophic, acyclovir resistant
HPV - extensive, recalcitrant, dysplastic
(also penicilliosis/histoplasmosis)
What neurological presentations can HIV cause?
- HIV assoc. cognitive impairment
- progressive multifocal neuroencephalopathy
- distal sensory polyneuropathy
- mononeuritis multiplex
- vacuolar myelopathy
- aseptic meningitis
- G-B syndrome
- viral meningitis
- cryptococcal meningitis
- neurosyphillis
What is HIV assoc. cognitive impairment?
-reduced short term memory with motor dysfunction
progressive multifocal neuroencephalopathy:
- what organism causes this?
- what s/s seen?
Organism: JC virus/reactivation latent virus
S/S: rapidly progressive, focal neurology, confusion, personality change
What is slim’s disease? what are the causes?
HIV assoc. wasting
- metabolic (chronic immune activation)
- GALT is wiped out
- anorexia
- diarrhoea
- malabsorption
- hypogonadism
What cancer is assoc. with HIV? what is this caused by? what is this treated with?
Kaposi sarcoma: vascular tumour
Non-hogkins lymphoma
cervical cancer
Kaposi sarcoma:
what is this caused by? what is this treated with?
-HPV
Treatment: HAART/local therapies/systemic chemo
